Mix of grafted and non-grafted particles in a resin

Abstract

In one application the mix grafted and non grafted invention provides for high thermal conductivity resin that comprises a host resin matrix 32 with a first class of grafted 31 high thermal conductivity particles that are grafted to the host resin matrix. Also a second class of non-grafted 30 high thermal conductivity particles that are not directly grafted the host resin matrix 32. The first class and the second class comprise approximately 2-60% by volume of the high thermal conductivity resin. The first class of grafted particles and the second class of non-grafted particles are high thermal conductivity fillers are from 1-1000 nm in length, and have an aspect ratio of between 3-100.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is a continuation-in-part of U.S. application Ser. No. 11 / 152,986, “High Thermal Conductivity Materials with Grafted Surface Functional Groups” filed Jun. 14, 2005, by Smith, et al., which is incorporated herein by reference.FIELD OF THE INVENTION[0002]The field of the invention relates to high thermal conductivity materials with surface grafted functional groups impregnated into resins.BACKGROUND OF THE INVENTION[0003]With the use of any form of electrical appliance, there is a need to electrically insulate conductors. With the push to continuously reduce the size and to streamline all electrical and electronic systems there is a corresponding need to find better and more compact insulators and insulation systems.[0004]Various epoxy resin materials have been used extensively in electrical insulation systems due to their practical benefit of being tough and flexible electrical insulation materials that can be easily adher...

AI Technical Summary

Benefits of technology

[0009]With the foregoing in mind, methods and apparatuses consistent with the present invention, which inter alia facilitates the transport of phonons through a high thermal conductivity (HTC) impregnated medium to reduce the mean distances between the HTC materials below that of the phonon mean free path length. This reduces the phonon scattering and produces a greater net flow or flux of phonons away from the heat source. The resins may then be impregnated into a host matrix medium, such as a multi-layered insulating tape.

[0010]High Thermal Conductivity (HTC) organic-inorganic hybrid materials may be formed from discrete two-phase organic-inorganic composites, from organic-inorganic continuous phase materials based on molecular alloys and from discrete organic-dendrimer composites in which the organic-inorganic interface is non-discrete within the dendrimer core-shell structure. Continuous phase material structures may be formed which enhance phonon transport and reduce phonon scattering by ensuring the length scales of the structural elements are shorter than or commensurate with the phonon distribution responsible for thermal transport, and / or that the number of phonon scattering centers are reduced such as by enhancing the overall structural order of the matrix, and / or by the effective elimination or reduction of interface phonon scattering within the composite. Continuous organic-inorganic hybrids may be formed by incorporating inorganic, organic or organic-inorganic hybrid nano-particles in linear or cross-linked polymers (including thermoplastics) and thermosetting resins in which nano-particles dimensions are of the order of or less than the polymer or network segmental length (typically 1 to 50 nm or greater). These various types of nano-particles may contain reactive surfaces to form intimate covalently bonded hybrid organic-inorganic homogeneous materials. Similar requirements exist for inorganic-organic dendrimers which may be reacted together or with matrix polymers or reactive resins to form a continuous material. In the case of both discrete and non-discrete organic-inorganic hybrids it is possible to use sol-gel chemistry to form a continuous molecular alloy. The resulting materials will exhibit higher thermal conductivity than conventional electrically insulating materials and may be used as bonding resins in conventional mica-glass tape constructions, when utilized as unreacted vacuum-pressure impregnation resins and as stand alone materials to fulfill electrical insulation applications in rotating and static electrical power plant and in both high (approximately over 5 kV) and low voltage (approximately under 5 kV) electrical equipment, components and products.

[0020]In particular embodiments the second class of non-grafted particles have an average length of 2-10 times that of the first class of grafted particles. Applications of this embodiment include the longer, non-grafted particles increasing the thermal conductivity, while the shorter grafted particles increase localized strength of the resin. In some embodiments a third class of non-grafted particles that are not high thermal conductivity particles are present in the host resin matrix.

[0021]In other particular embodiments at least a portion of the first class of grafted particles are high thermal conductivity fillers from 1-1000 nm in length, and have an aspect ratio of between 3-100. In other embodiments the grafted particles increase the dielectric strength of the host resin matrix.

Problems solved by technology

Most inorganic materials do not allow independent selection of structural characteristics such as shape and size and properties to suit different electrical insulation applications or to achieve composites having the right balance of properties and performance.

Images